1. Field of the Invention
The present invention relates to a motorcycle's rearview mirror support structure.
2. Description of Background Art
Support structures for a motorcycle's rearview mirror are known. For example, Laid-open Japanese Patent No. Sho 51-25316, titled "A Safe Rearview Mirror," and Laid-open Japanese Patent No. Sho 58-28917, titled "A Structure for Supporting Rearview Mirror of a Vehicle" describe rearview mirror support structures. The rearview mirror support structures of these two Japanese Patents are similar to the support structure illustrated in FIGS. 5(a) and 6(a), which will be described in greater detail later in the specification. However, for purposes of an introduction to the background art, the two Japanese Patents will be briefly described.
Japanese Patent No. Sho 51-25316 shows a half-spherically convex portion of a case 5 engaged with a half-spherically concave portion of an fitting leg 1. A pressure is applied by a spring 3, through a half-spherical body 2, from the inner side of the half-spherically convex portion, so as to rotatably attach the case 5 to the fitting leg 1. The attachment is made by a screw 4. A mirror 6 is fixed to the case 5.
In this rearview mirror, a spring bracket surface for the spring 3 is provided on the half-spherical body 2. The spring bracket surface is planar. Because the spring bracket surface is planar, the pressure of the spring 3 is not applied uniformly till the end of the half-spherically convex portion of the case 5. As a result, the mirror 6 may vibrate. Further, when the case 5 is moved in order to adjust the mirror 6, the rearview mirror may rattle, depending upon the rotational position of the case 5.
Japanese Patent No. Sho 58-28917 shows a spherical supported portion 15 of a main body M of a rearview mirror as being exposed to a stay seat 3 of a stay 1 for supporting the rearview mirror through a lower elastic body 4. The main body M of the rearview mirror is rotatably held on the inner surface of the spherical supported portion 15 by a pressing force of a compression spring 13 through an upper elastic body 5 and a spring bracket 6.
A drawback results from the lower elastic body 4 being sandwiched between the stay seat 3, which is used as a sliding surface, and the spherical supported portion 15. When the main body M of the rearview mirror is adjusted by an operator of the motorcycle, the sliding between the stay seat 3 and the spherical supported portion 15 is not smooth. A